Rose Rosette in Annex, Toronto


Hi Toronto Master Gardeners – hope all is well.

My newly planted young rose bushes (Double Knock Out, Floribunda, Grandiflora and Hybrid Tea Roses) are producing new leaves and stems in bright burgundy color with extra thorns. Older thorns and stems are turning reddish as well. I’m very worried it could be Rose Rosette, but I’m no expert and this is my first year of growing roses in Toronto.

Please advise. Thank you.

Warm regards,


It is very hard to tell from your picture if indeed your plants have Rose Rosette.  A lot of new growth on roses is red/burgundy and then as it matures and grows, the leaves turn lovely shades of green.  There are a few basic things to learn when growing roses, see below.

  1. Planting where rose gets 6 hours or more of direct sunlight.
  2. Planting at the correct depth, soil level should be just below the graft.
  3. Proper spacing between rose plants will help with insect and disease transfer between plants.
  4. Mounding of the graft in fall to protect from winter damage.
  5. Proper pruning in late winter/early spring.
  6. Fertilizing with recommended Rose food.
  7. Checking regularly for disease and insect infestations and treat where appropriate.

Below you will find a link to a great article about Rose Rosette.  I recommend you read it and compare the pictures with what your own plants are doing as this will make your diagnosis easier.  If you determine that one of your plants seems to have this “witches broom” effect caused by a virus spread by mites, then digging up and destroying this plant is the only option.

Good luck.